Unhealthy-sounding metallic rasp at 4K
 

Earlier this year, I upgraded to the following mods:

Perrin 2.5" resonated catback
Custom catted front pipe
Custom over pipe
Perrin CAI

Sounded great, happy with it.

Two months later, I got an ECUTEK tune. After that, I would get a very nasty, unhealthy metallic rasp around 4000 RPM.

Have no idea what is except it happened after the tune? Is it possible this was caused
by the tune???

It only happens when you apply hard throttle (it's fine when being gentle), and it only happens when the car is in gear (could not replicate the sound when revving in neutral).

Any help would be awesome.




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Don't worry about it. The OFT tune does the same thing. Something to do with VVT harmonics or something. It's been discussed previously in the tuning section I believe.

White, that rasp you are hearing is caused by the aggressive change in the VVT to help with the torque dip many tuners apply..

It's nothing to be concerned about. It can be heard on the stock tune as well however its less aggressive.

Ok that makes me feel a bit better. I was concerned the piping might be faulty. However, I do have a friend with an almost identical setup, but no rasp. Explain that?!

I'm putting in the SpeedFactory UEL headers in next week -- is this going to make it worse?


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He is tuned as well?

Define almost identical?

A different intake as in your case could definitely make it more audible. Does he have a tune? Is it from the same tuner? His VVT timing may not be as aggressive.

If you're that concerned talk to your tuner, however that "sound" is quite normal on tuned cars, it all depends on how aggressive the tune is.

Same tuner and CBE. Different FP and intake. Plus he had RevWorks headers. I'm guessing the headers would make for a less aggressive tune?


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I know in the case of the OFT and a few other remarks, yes the VVT change is less aggressive with a tune including a header.

I have the same noise. The noise came in after about 14k miles after I got a dyno tune. :(

The resonance will be less noticeable if you have a header since the tune will likely be less aggressive in trying to tune out the torque dip. There's nothing dangerous about it, and there are a couple threads in the tuning section about it.

I had the noise on the stock tune as well, it's just more pronounced with an aftermarket tune.

Make sure the piping after the midpipe isn't hitting the diff. Might want to check any v-band clamps and other flange connections too.

I made a big stink about it with my tuning. And had Perrin strip the VVT "optimaztion" out and sound was gone. No one can prove if its bad long term or not or why the systen makes the noise. Some people with the same tune dont have the noise because after the flash process the VVT/cam calibration does not finish as they drive off right after.

I tried that a few times to see and it randomly made no noise.

I've heard the sound enough on mine with the stock tune to not even think twice about it anymore.

It's not a metallic clangining, it is most definitely just resonance/rasp. It doesn't always happen in a given RPM range, it has to be under certain circumstances. It also happens for sure a small window that it's definitely a resonance.